Isolation of Adipose Tissue-Derived Stem Cells: Enzymatic Digestion in Combination with Mechanical Distortion to Increase Adipose Tissue-Derived Stem Cell Yield from Human Aspirated Fat.

Mesenchymal stem cells (MSCs) are of great interest due to their properties of immune modulation, tissue regeneration, and multipotent differentiation. Future developments of clinical applications, however, require a higher yield of MSCs, lower number of passages of cells in culture, and shorter time from harvest to use. Optimization and standardization of techniques for mesenchymal adipose tissue-derived stem cell isolation offers solutions to current bottlenecks as a larger amount of MSCs can be isolated. These improvements result in shorter expansion time, fewer passages, less donor material needed, and higher MSC yield. This paper describes an MSC isolation method combining enzymatic digestion with mechanic disruption. This protocol is a standardized and easy-to-implement method for reaching significantly higher MSC yields compared to conventional enzymatic isolation protocols. Based on the results presented, we hypothesize that the combined enzymatic and mechanical method increases the surface area of the adipose tissue, facilitating digestion by enzymes. This approach reduces the amount of adipose tissue and in vitro expansion time needed to reach sufficient amounts of MSCs for clinical purposes. Importantly, the method does not require increased amounts of collagenase, nor does it impair the viability or differentiability of the MSCs. Using this protocol increases MSC yield by a factor of three. As a consequence, these results indicate that the physiological concentration of MSCs in adipose tissue is higher than previously assumed.